If you go back about 3500 years ago, the Late Bronze Age was going pretty smoothly with big, fairly stable civilizations / empires in the Fertile Crescent, Egypt, and Greece.
But around 1200 B.C. most everything fell apart, leading to a dark age out of which eventually emerged a new Iron Age civilization. For example, the Trojan War was so famous in Greece subsequently because it was a glamorous late event in a high Bronze Age civilization that had shortly afterwards declined. It was the writing down of the Homeric epics about the Trojan War several hundred years later that marked the revival of related-but-new high civilization in Greece.
Here’s an interview with GWU professor Eric H. Cline promoting his book 1177 BC: The Year Civilization Collapsed.
May 20, 2015
written by James Wiener
Cline downplays the famous but mysterious Sea People who fought the Egyptians in 1177 BC as a chief cause.
… Of these, I would rank them in that specific order of importance: climate change; drought and famine; earthquakes; invaders; and internal rebellions. Although human beings have survived such catastrophes time and again when they come individually, such as rebuilding after an earthquake or living through a drought, what if they all occurred at once, or in quick succession?
But what if it were technological change itself that was the impetus in the transition from Bronze Age to Iron Age? It wouldn’t be the first time that barbarians with better weapons overran more sophisticated civilizations.